This invention relates to a method for forming cutting tools and specifically rotary cutting tools with diamond-like cutting edges and inserts for drag bits with diamond-like secondary cutting surfaces which are formed by bonding high shear compaction diamond-like rope or strip material in helical grooves formed on the cutting tool bodies. "Diamond-like" as used herein refers to ultra hard materials including diamond and cubic boron nitride (CBN).
Rotary cutting tools are used in a variety of machining operations. Helically fluted end mills and ball end mills are commonly used rotary cutting tools and are generally required to perform severe machining operations under adverse conditions, as well as, finishing operations where a fine surface is desired. The cutting end of a helically fluted end mill, for example, includes at least one cutting edge on the end mill blank. The cutting end of a ball end mill carries the cutting edge around the ball end of the mill. Other types of rotary cutting tools include diamond twist drills, composite sintered twist drills, printed circuit board drills, reamers and taps.
Similarly, inserts with secondary cutting surfaces formed on a side surface of the insert substrate (body) are used as the cutting elements in a drag bit. The primary cutting surface of drag bit insert is typically a diamond layer 140 sintered on a face of the insert body (FIG. 6). The secondary cutting surfaces are formed by packing and sintering diamond crystals (or CBN) in grooves formed on the substrate (body).
The cutting tools have cutting surfaces formed by sintering a diamond-like material on grooves formed on their outer surfaces. After sintering, the diamond-like material is machined to form a sharp cutting surface edge. Compaction is required to ensure sufficient density of diamond within the groove to minimize material shrinkage during the sintering process. An increase in the density of the diamond-like material improves the impact resistance or toughness, wear resistance and material uniformity of the cutting surface. Current methods of compacting the diamond-like material are complex resulting in quality inconsistencies between cutting surfaces.
Accordingly there is a need for a method for manufacturing cutting tools where a high compaction of the diamond-like material is easily achieved, minimizing the shrinkage of the diamond-like material during the sintering process, resulting in improved impact resistance or toughness, wear resistance, and uniformity.